def demo(obj):
    print("形参值：",obj)
    obj += obj
    print("形参值：",obj)

print("==========值传递=========")
string = "这是第一个测试" 
print("调用函数前实参值：",string)
demo(string)
print("调用函数后实参值：",string)
print("==========引用传递=========")
list1 = ['1','2','3','4'] 
print("调用函数前实参值：",list1)
demo(list1)
print("调用函数后实参值：",list1)
